K.
Have you gotten your period back yet? Is it possible that you are having it now/getting it soon? I haven't yet, but I hear that can cause things to taste "off". Check for pregnancy too - my son definitely changed his habits when I became pregnant with my daughter, which happened when he was 16 months old.
My daughter's the same age almost exactly now, and she definitely has strong feelings about either wanting to nurse or not, one side or the other. It's so frustrating when you don't know what they're looking for. At this point my girl prefers the left side and nurses from it 2-3x/day, but will only nurse from the right side when she's quite sleepy or just woke up in the morning. I figure that side will be done first, and that's ok at this point - whatever works for her.